Piston expander



-W. C. KNOEBEL PISTON EXPANDER Dec. 28, 1937.

5 Sheet S-Sheet 1' Filed March 25, 1937 FIG I FIGZ.

It h 3 L 5 w m mm m m R /W m- Y .W

W. C. KNOEBEL PISTON EXPANDER Dec. 28, 1937.

3 Sheets-Sheet 2 Filed March 25, 1937 FIG.6.

FIG.8.

INVENTOR. WALTER O. KNOEBEL A ORNEY Q Patented Dea -28, 1937 PISTON EXPANDER Walter C. Knoebel, KirkwoodQMm, asslgnor to Dallas M. Smith, Kirkwood, Mo.

Application March 25, 1937, Serial No. 133,061

6 Claims.

My invention relates to piston expanders and more particularly to expanders designed to be inserted in pistons used in internal combustion engines and arranged to increase the effective dimensions of the skirts of such pistons to compensate for wear resulting from operation of the engine.

Expanders of this type as heretofore used have been made in widely varying shapes and forms, some of the expanders have comprised resilient spring members anchored at each side of the axially extending slot in the piston skirt, but these expanders by opening up the slot and increasing the circumference of the skirt in this way increased the diameter of the skirt at the pin bosses whereas the diameter of the skirt for most effective operation should beincreased at points removed about ninety degrees from the bosses. Expanders'designed to increase the diameter properly have usually comprised members arranged to extend inside of the piston skirt and to contact substantially diametrically opposed points, but because of the vibration and flutter set up in the resilient skirt of a piston great difficulty has been met in maintaining such expanders in proper position and preventing them from becoming dislodged during. operation and falling into the crank case of the engine with resultant injury and damage to the working parts thereof.

The means used for maintaining expanders in position in the piston have taken many different forms. For instance, the contacting parts of the expander have been riveted or boltedto the piston skirtbut because of the comparative thinness of the skirt wall often this method of attachment resulted in rupture of the wall with great damage to the cylinder in which the piston reciprocates. Other types of expanders have included openings through which the wrist pin extends but if such expanders become loose and expander which will exert a proper expansive force against the skirt of the piston and yet will be simple in design, efficacious in operation and low in cost.

While the broad concept of my invention may be embodied in many different forms and types of expanders, in the accompanying drawings wherein similar characters are used to designate similar'parts, I have shown only a few of the forms or embodiments which my invention may take. In these drawings, Fig. 1 is a cross section of a piston including one embodiment of my. invention; Fig. 2 is a longitudinal section along the lines 22 in Fig. 1; Fig. 3 is a transverse section along the lines 3-3 in Fig. 1; Fig. 4 shows the expander and attaching means in detail; Fig. 5 is a longitudinal section of a piston including a modified form of an expander; Fig.

6 is a section along the lines 6--6 in Fig. 5; Fig;

move relative to the wrist pin a severe shearing and cutting action is set up which in many instances severs the wrist pin,

All of the .methods of attachment heretofore used have supported the expander either on the wrist pin or bosses or other parts carried by or included in the resilient and expansible skirt of the piston and, as stated above, it is the skirt which vibrates and flutters during operation. Therefore, such methods of attachment have been ineffectual and insecure.

Having in mind these and other deficiencies of expanders heretofore used the objects of my invention are to provide a piston expander and method of support therefor wherein the expander will be fixed and secured to the head of the piston as distinguished from the resilient skirt thereof; to provide an expander which will be maintained in place securely and positively; and provide an 7 is a section along the lines 1-l in Fig. 5; Fig.

8 is an end view of the expander removed from the piston; Fig. 9 is a longitudinal section of a piston including still another form of the expander; Fig. -10 is a view along the 1ines'-l0l0 in Fig. 9; Fig. 11 is a view of a piston including a fourth embodiment of my invention; and Fig. 12 is a bottom view of the assembly as shown in Fig. 11.

Referring to the figures and particularly to Figs. 1 to 4, inclusive, the piston shown therein as including my invention comprises a head A and a skirt B depending therefrom and separated from the head throughout a portion of its circumference by circumferentially extending slots C. The head A includes a ring belt, D and the skirt B is split axially of the piston as at E. Also,

of course, the piston comprises the usual pin bosses F arranged to receive the wrist pin G upon which is mounted the head of a connecting rod H.

In the embodiment shown in Figs. 1 to 4, inclusive, the expander comprises a generally U- shaped piece of fiat spring metal J having depending legs K with the lower ends thereof formed generally arcuate in shape, as shown, to engage and exertan expansive force on the inner surface of the skirt B. Preferably, the expander is arranged in the piston to contact the skirt at opposed pointssubstantially ninety degrees from the bosses so that proper expansion of the skirt willjbe obtained.

In the embodiment shown here the expander is secured to the head of thepiston by means of a rod L extending between holes arranged at diametrically opposed points in the head of the piston and leading, preferably, from the bottom of the lower ring groove. As shown in Fig. 1 when the expander is in place in the piston the resiliency of the expander'and the expansive force created thereby will distort the rod L and bend it into a shape which has beenexaggerated in Fig. ,1. Such bending will put the rod under tension relative to the expander and also will put the ends of the rod under tension in the holes inwhich it is anchored to the head A of the piston.

From the above description it will be seen that an expander embodying my invention when mounted in a piston in the manner shown will be held in place firmly and securely and there will be no danger that the expander will become accidentally dislodged to fall into the crank case. Of course, an ordinary piston ring, not shown, of any of the usual types is placed in the ring groove and, therefore, the rod L with such ring in place can not move or creep outwardly through the holes in the bottom of the groove receiving the piston ring.

In the embodiment shown in Figs. 5 to 8, inclusive, the expander proper is formed of spring wire and the legs K are formed by downwardly extending loops of wire each of which loops engages and exerts an expensive force on the piston skirt. Preferably, the expander is formed of a single piece of wire which has the ends thereof welded so that the loops are integral with one another. At the upper parts of the expander is arranged a pair of bars M through which extend the parallel side portions formed by-the wire. Substantially centrally of each bar M is a hole N through which an attaching rod L" extends. The rod L will be bowed when the expander is in place and when the rod is positioned in the openings in the bottom of the lower ring groove in a manner similar to the rod L described in the first embodiment. In this form the outer ends of the rod L are threaded to receive lock nuts X whereby additional security is given that the rod will be held in place firmly.-

In the embodiments which have been described hereinbefore the expander is supported by and secured to the head of the piston by means of a rod extending across the hollow interior of the head. This rod may be arranged axially of the bosses and at right angles to the expander and the expander itself may be mounted on the rod by any one of a number of expedients other than those shown. In both embodiments shown the supporting means for the expander will not be directly subjected to the vibrations and flutter of the resilient skirt.

In other embodiments of my invention the expander either of the U shape as shown or of any other type or shape may be secured to the head of the piston by other expedients. For instance, in Figs. 9 and 10 the expander J is firmly secured to the head of the piston by means of a bolt P threaded into the head, preferably, at the center thereof. A sleeve Q may be arranged between the piston head and the expander so that the expander will be spaced from the head as desired. When the bolt P is drawn tightly into place the expander will be anchored to the head and will be firmly secured thereto.

In Figs. 11 and 12, the expander J is mounted on and firmly secured to the bracket R and, in turn, this bracket is secured to the head of the piston by studs S threaded in the head. The expander J may be secured to the bracket R by welding, brazing or by any other suitable expedient as the pin T, as shown in Fig. 11. Preferably, the bracket R is arranged with flanges U extending in opposed directions, as shown in Fig. 12,

pander may take difierent forms and shapes, but,

it is to be understood, other embodiments not shown and described herein may be made in a wide variety of forms and shapes without deviat ing from the spirit of my. invention as included in the appended claims.

What I claim as new and desire to secure by Letters Patent, is: v 1. A piston expander including parts arranged to engage the piston skirt and exert an expansive force thereon, a rod adapted and arranged to extend across the hollow interior of the head of the piston in which said expander is used, and said skirt engaging partsbeing secured to said rod.

2. A piston expander including a pair of legs arranged so that the lower ends thereof engage the piston skirt at diametrically opposed points to exert an expansive force thereon, a rod extending across the hollow interior of the head of the piston in which said expander is used, and the upper ends of said legs being secured to said rod.

3. A piston expander including resilient parts arranged to engage the piston skirt and exert an expansive force thereon, supporting means adapted to be secured to the piston head away from the piston skirt and being otherwise positioned and arranged whereby said, supporting means will not be subjected directly to vibrational movement of said skirt, and the resilient parts of said expander being secured to said supporting means.

4. A piston expander including parts arranged to engage the pistonskirt at diametrically opposed points and to exert an expansive force on said skirt, supporting means adapted to be secured to the piston head away from the piston skirt and being otherwise positioned and arranged whereby said supporting means will not be subjected directly to vibrational movement of said skirt, and said expander being secured to said supporting means.

5. A piston expander including a pair of downwardly extending legs having the lower ends thereof arranged to engage the piston skirt and exert an expansive force thereon, supporting means adapted to be secured to the piston head away from the piston skirt and being otherwise positioned and arranged whereby said supporting means will not be subjected directly to vibrational movement of said skirt, and the upper ends of said legs being attached to said supportingmeans.

6. The combination with a piston, having a resilient skirt separated from the head of said piston by circumferentially extending slots, of a piston expander including resilient parts arranged to engage the piston skirt and exert an expansive force thereon, supporting means adapted to be secured to the piston head away from the piston skirt and being otherwise positioned and arranged whereby said supporting means will not be subjected directly to vibrational movement of said skirt, and the resilient parts of said expander being secured to said supporting means. 

